We propose to: a) Continue detailed chemical structural studies of the erythrocyte membrane surface sialoglycoprotein; these studies will lead directly to precise mapping of various antigenic and lectin binding sites. b) In studies of assembly of surface glycoproteins to continue investigations of biosynthesis of membrane proteins of rabbit erythrocytes and reticulocytes. c) In studies of assembly of lipid components of cell membranes to continue investigations of mechanism of insertion of cholesterol into cell membranes. To elucidate the chemical nature of membrane components responsible for attachment of diploid cells in culture to surfaces on which they grow.